Humans are hard-wired to form enduring bonds
with others. One of the primary bonds across the mammalian
species is the mother-infant bond. Evolutionarily speaking,
it is in a mothers best interest to foster the well-being
of her child; however, some mothers just seem a bit more maternal
than others do. Now, new research points to a hormone that
predicts the level of bonding between mother and child.
In animals, oxytocin, dubbed the hormone of love and
bonding, is critically important for the development
of parenting, is elicited during sexual intercourse, and is
involved in maintaining close relationships. Animals with
no oxytocin exhibit slower pup retrieval and less licking
and self-grooming. These findings implicate oxytocin in the
bonding process, but little research has been done on this
relationship in humans.
Ruth Feldman, psychology professor at Bar-Ilan University
in Israel, conducted the first study to demonstrate the links
between oxytocin and bonding in human mothers. Feldman and
colleagues measured plasma oxytocin from sixty-two pregnant
women during their first trimester, third trimester, and the
first postpartum month.
They also observed the mother and child interact, defining
the level of attachment along four aspects: gaze, affect,
touch, and vocalization. Stronger attachment would mean that
the mother focused her gaze mostly on the child, exhibited
a positive energy towards the child, maintained constant affectionate
and stimulating touch with the child, used a motherese
speech with the child, and these species-typical maternal
behaviors were adapted to the infant's alert state.
After the mothers completed an extensive survey and an interview
on their bond-related thoughts, feelings, and behaviors, the
researchers computed the link between levels of oxytocin and
bonding.
The results are fascinating. Initial levels of oxytocin at
the first trimester predicted bonding behavior. Therefore,
mothers with a high level of the hormone at the beginning
of the pregnancy engaged in more of the aforementioned bonding
behaviors after birth.
Additionally, mothers who had higher levels of oxytocin across
the pregnancy and the postpartum month also reported more
behaviors that support the formation of an exclusive relationship
(i.e. singing a special song to the infant, or bathing and
feeding them in a special way). These mothers were also more
preoccupied by thoughts of checking on the infant, the infants
safety when they are not around, and the infants future.Â
This study, which appears in the November issue of Psychological
Science, a journal of the Association for Psychological Science,
suggests that women with higher levels of oxytocin during
their first trimester are primed to the formation of an exclusive
bond with their infants. Oxytocin seems to be preparing mothers
to engage in bonding behaviors. The findings also show that
oxytocin is related to the mental, as well as the behavioral,
aspect of bonding. More generally, this study confirms that
there is a cross-species continuity in mechanisms that underlie
species-specific expressions of bonding.